This application is based on application No. 10-359079 filed in Japan, the contents of which is hereby incorporated by reference.
1. Field of the Invention
The present invention relates generally to control systems and particularly to control systems for remotely controlling a mobile robot via a network.
2. Description of the Related Art
There has been a demand for automation of the maintenance and check of locations too dangerous to enter, such as factories, atomic power plants. There has also been a demand for automation of patrol in buildings, particularly night patrol, considering the issue of personnel expenses. Such maintenance and check and patrol can be automated by installing various types of sensors or the like at locations required to be checked. If a large area must be thoroughly checked, however, a multitude of sensors must be installed and an extremely increased cost will be required for installing the sensors. To overcome this disadvantage, there has been provided a mobile robot known as having a scheme allowing the robot to move around in an area freely to observe in detail the environment surrounding the robot. This robot can move in any directions, with a charge coupled device camera (referred to as a CCD camera hereinafter) mounted thereto so that the environment surrounding the robot can be imaged. The mobile robot can be moved to a location to be checked and a site to be checked can be imaged with the CCD camera. As such, automation of check for the purpose of maintenance, and patrol can be achieved at low cost.
A conventional mobile robot is adapted to communicate with a control device for controlling the robot, to receive an operation instruction and make a movement accordingly. If there is an obstacle in the direction in which the robot moves, the robot must change its route or stop to avoid the obstacle. Such operation instructions as route change, stop are input by the operator to the control device and thus transmitted to the robot, as appropriate. The robot sends to the control device the positional information of the robot and the moving images provided by the CCD camera. The operator uses the information and images displayed on a display, to determine the environment surrounding the robot and accordingly input an operation instruction indicative of an subsequent operation to be performed by the robot.
However, if the mobile robot and the control device transmitting operation instructions to the robot do not communicate via a dedicated line but a network used by an uncertain, large number of users, such as the Internet, constant data communication rate cannot be ensured in the communications between the robot and the control device. As such, the time elapsing after the robot transmits to the control device an image provided by the CCD camera and before the robot receives an operation instruction determined based on the transmitted image, varies with the network""s communication rate. If the network uses the Internet its communication rate varies, e.g., with the number of users and it is thus difficult to predict how the communication rate varies. As such, when with a communication rate extremely reduced an operator monitoring a moving image on the control device""s display finds that the robot will collide with a wall and the operator accordingly transmits an operation instruction to stop the robot, the robot may have already collided with the wall.
To overcome the above disadvantage, one object of the present invention is to provide a control system capable of correcting a deficiency associated with delayed transmission of an instruction resulting from increased communication load.
Another object of the present invention is to provide a control system capable of safely and reliably controlling an operation unit.
Still another object of the present invention is to provide a mobile robot system capable of correcting a deficiency associated with delayed transmission of an instruction resulting from increased communication load.
Still another object of the present invention is to provide a mobile robot system capable of safely and reliably controlling a mobile robot.
Still another object of the present invention is to provide a control method capable of correcting a deficiency associated with delayed transmission of an instruction resulting from increased communication load.
Still another object of the present invention is to provide a control method capable of safely and reliably controlling a robot.
To achieve the above objects, in one aspect of the present invention the control system controlling an operation unit performing a plurality of operations includes an instruction unit to transmit an instruction to the operation unit via a communications line to control the operation, a detector to detect a load of a communication between the operation unit and the instruction unit, and an operation controller to limit a predetermined one of the plurality of operations depending on a detection result from the detector.
In accordance with the present invention, a detection result from the detector can be used to limit a predetermined one of the plurality of operations. As such there can be provided a control system capable of correcting delayed transmission of an instruction associated with increased communication load. Furthermore there can be provided a control system capable of safely and reliably controlling the operation unit.
In another aspect of the present invention, the mobile robot system includes a self-propelled mobile robot to perform a plurality of operations, a remote control device to transmit to the mobile robot an instruction for controlling the operation, a detector to detect a load of a communication between the mobile robot and the remote control device, and an operation controller to control the operation of the mobile robot depending on a detection result from the detector, regardless of the instruction from the remote control device.
In accordance with the present invention, a detection result from the detector can be used to control an operation of the mobile robot, regardless of the instruction from the remote control device. As such there can be provided a mobile robot system capable of correcting delayed transmission of an instruction associated with increased communication load. Furthermore there can be provided a mobile robot system capable of safely and reliably controlling the mobile robot.
In accordance with the present invention, in still another aspect the method of remotely controlling a robot performing a plurality of operations includes the steps of transmitting an operation instruction from a remote device to a robot, detecting a load of a communication between the remote device and the robot, and controlling an operation of the robot depending on a detected communication load, regardless of the operation instruction from the remote device.
In accordance with the present invention, depending on the detected communication load an operation of the robot can be controlled, regardless of the operation instruction from the remote device. As such there can be provided a control method capable of correcting delayed transmission of an operation instruction associated with increased communication load. Furthermore there can be provided a method capable of safely and reliably controlling an operation of the robot.
The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings.